Conventional, so-called image guided systems (IGS), also referred to as surgical navigation systems, are becoming more common and widely adapted in surgeries including neurosurgery. Examples include, for example, navigation systems that use electromagnetic sensors or cameras with optical fiducials for tracking and registering tools and patients from an imaging space to a surgical space. Currently, many IGS systems are based on obtaining a pre-operative series of imaging data, such as, e.g., MM and CT images which are registered to the patient in the physical world or surgical space and which include tracking systems for navigation during surgery. Optical tracking allows for detecting markers placed on a patient's skin and/or and surgical tools (known as “fiducials”) using a camera for registration between an imaging space and a surgical space. Electromagnetic (“EM”) tracking systems are also used for surgical navigation. See, e.g., U.S. Pat. Nos. 7,706,600; 7,491,198; and 8,238,631 and US Patent Application Publications 2004/075768; 2012/0330135; and 2013/0060146, the contents of which are hereby incorporated by reference as if recited in full herein.